diff options
| author | Kees Cook <keescook@chromium.org> | 2012-10-19 13:56:51 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-19 14:07:47 -0700 |
| commit | 2702b1526c7278c4d65d78de209a465d4de2885e (patch) | |
| tree | a41af3d56a6e37af19bc7ed392f2580750ba86cb /kernel | |
| parent | 1d46e232f8637f31f8df2e50b27fd20d8135bd93 (diff) | |
| download | lwn-2702b1526c7278c4d65d78de209a465d4de2885e.tar.gz lwn-2702b1526c7278c4d65d78de209a465d4de2885e.zip | |
kernel/sys.c: fix stack memory content leak via UNAME26
Calling uname() with the UNAME26 personality set allows a leak of kernel
stack contents. This fixes it by defensively calculating the length of
copy_to_user() call, making the len argument unsigned, and initializing
the stack buffer to zero (now technically unneeded, but hey, overkill).
CVE-2012-0957
Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sys.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index c5cb5b99cb81..01865c6fb6a0 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1265,15 +1265,16 @@ DECLARE_RWSEM(uts_sem); * Work around broken programs that cannot handle "Linux 3.0". * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40 */ -static int override_release(char __user *release, int len) +static int override_release(char __user *release, size_t len) { int ret = 0; - char buf[65]; if (current->personality & UNAME26) { - char *rest = UTS_RELEASE; + const char *rest = UTS_RELEASE; + char buf[65] = { 0 }; int ndots = 0; unsigned v; + size_t copy; while (*rest) { if (*rest == '.' && ++ndots >= 3) @@ -1283,8 +1284,9 @@ static int override_release(char __user *release, int len) rest++; } v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40; - snprintf(buf, len, "2.6.%u%s", v, rest); - ret = copy_to_user(release, buf, len); + copy = min(sizeof(buf), max_t(size_t, 1, len)); + copy = scnprintf(buf, copy, "2.6.%u%s", v, rest); + ret = copy_to_user(release, buf, copy + 1); } return ret; } |